JPH06328607A - Damping sheet - Google Patents

Abstract

PURPOSE:To provide a damping sheet enhanced in damping capacity by setting the modulus of elasticity of the adhesive layer bonded to an adherend at the normal temp. to a specific value and allowing the adhesive layer to enter a rough surface to develop anchoring effect to enhance the adhesiveness thereof. CONSTITUTION:In a damping sheet 1 having a three-layered structure consisting of a highly elastic restriction layer 2, a viscoelastic elasticity of the adhesive layer 4 at the normal temp. is set to 10<6>-10<10>dyne/cm<2>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration-damping sheet which is directly attached to a vehicle such as an automobile, a home electric appliance, an OA device, a building-related product for vibration damping.

[0002]

2. Description of the Related Art For a continuously vibrating vehicle such as an automobile, a so-called viscoelastic material converts mechanical energy due to vibration into heat energy by internal heat generation and dissipates the energy, thereby causing vibration of a panel or the like. Damping processing is performed to reduce the generation of noise by damping.
In addition to automobiles, transportation equipment such as railway vehicles and aircraft, industrial equipment such as hoppers and crushers, building materials, buildings such as bridges, OA
It is also widely used in equipment and home appliances.

The vibration damping sheet is a material that utilizes the characteristics of the viscoelastic substance to damp the vibration of the structure and reduce the noise generation, and this vibration damping sheet has a point of action mechanism. Therefore, it is roughly divided into the following two types.

That is, the first is a single-layer type vibration damping sheet for damping the vibration of the vibration-damped body by utilizing the internal heat generated by the expansion and contraction of the viscoelastic substance, and the second is the viscoelastic substance relatively. It is a laminated type vibration damping sheet in which shearing deformation is caused by sandwiching with a constraining layer having a high elastic modulus to similarly reduce vibration.

As the above-mentioned first single-layer vibration damping sheet, a heat fusion asphalt sheet widely used as a vibration damping sheet for vehicle body panels of automobiles is well known. This is a solid sheet that does not show any fluidity at room temperature, and this sheet is left standing on the panel body to be subjected to vibration damping treatment during the automobile manufacturing process, and the heat applied when baking the thermosetting resin paint is applied. Utilizing this, the vibration damping process is performed by fusing it to the panel.

This is because the sheet thickness is made considerably thicker (3 to 10 mm) than that of the laminated vibration damping sheet, or the viscoelastic substance is kneaded with a high-density filler, whereby the internal heat of the viscoelastic substance is generated. In addition to the loss, the vibration damping process is performed by adding the weight (equivalent mass) of the entire vibration damping sheet.

In the second laminated vibration damping sheet, a viscoelastic substance, for example, an alkyl group having 4 carbon atoms is used.
An acrylate-based adhesive composition obtained by copolymerizing 10 to 10 alkyl acrylates, lower alkyl acrylates, lower alkyl methacrylates, vinyl acetate, etc., or natural rubber, styrene-butadiene rubber, butyl rubber, re-vulcanized reclaimed rubber, etc. An unvulcanized rubber composition obtained by blending a tackifier, a rubber softening agent, a filler and the like in one or more kinds is used for a metal thin plate such as aluminum which functions as a constraining layer in an amount of 0.1 to 0.1%. It is configured to be applied or laminated to a thickness of 3 mm and to be adhered onto a vibration body to be subjected to vibration damping treatment.

However, in the case of the above-mentioned first single-layer type vibration damping sheet, in order to obtain sufficient vibration damping characteristics, the vibration damping sheet layer must be made considerably thick, 3 to 10 mm, and as a result, the weight is reduced. When it becomes large and the weight of automobiles is required to be reduced, its use is significantly restricted.

Moreover, this type of vibration damping sheet has a large temperature dependence in its vibration damping characteristics, and has sufficient vibration damping properties at around room temperature, but hardly exhibits vibration damping properties at high temperatures of 40 ° C. or higher.

On the other hand, the second laminated type vibration damping sheet is thin and has high vibration damping characteristics as compared with the first single layer type vibration damping sheet, so that it can be made lighter, but Similar to the layered type vibration damping sheet, the vibration damping characteristics have a large temperature dependency, and at a high temperature of 40 ° C. or higher, the vibration damping characteristics hardly exist.

Therefore, recently, a vibration-damping sheet having a three-layer structure composed of a highly elastic constraining layer, a viscoelastic substance layer and an adhesive layer has been proposed.

[0012]

This damping sheet is used for transporting equipment such as railway vehicles, aircrafts, hoppers, etc. in addition to automobiles.
It is widely used for industrial equipment such as crushers, building materials, buildings such as bridges, office automation equipment, and adherends such as home appliances.

By the way, the surface of these adherends is not always limited to a smooth surface but is often a rough surface. In such a case, the conventional vibration damping sheet was expected. Since it is difficult to secure the adhesive force, there is a serious problem that the workability is remarkably deteriorated due to a natural drop after the adhesion to the adherend, a positional shift, and the like.

The present invention has been completed in order to solve the above technical problems, and in this type of laminated vibration damping sheet, the adhesive layer that adheres to the adherend exhibits fluidity when adhered. The elastic modulus at room temperature is 10 ⁶ to 10 ¹⁰ dyne / cm ²
It is an object of the present invention to provide a vibration-damping sheet having improved vibration-damping performance by improving the vibration-damping performance by improving the adhesive property by entering into the rough surface to exhibit the anchoring effect by setting to.

[0015]

In order to achieve the above object, the vibration damping sheet of the present invention is a vibration damping sheet having a three-layer structure comprising a high elastic constraining layer, a viscoelastic substance layer and an adhesive layer. In this adhesive layer, the elastic modulus at room temperature is 10 ⁶ to 10
It is characterized by being ¹⁰ dyne / cm ² .

The high elasticity constraining layer used in the present invention is not particularly limited as long as it holds and constrains the viscoelastic substance layer described later in a wide temperature range, and specifically, for example, aluminum. Examples include metal foil such as stainless steel and inorganic fiber cloth such as glass cloth.

The high elastic constraining layer has a thickness of 1
It is preferably 0 to 300 μm, particularly 30 to 200 μm. If the thickness is less than 10 μm, the effect as a constraining layer is low. On the other hand, if it exceeds 300 μm, the thickness is too thick, so that the vibration damping sheet lacks flexibility, and the workability for sticking to a curved surface is reduced, and the weight increases. In addition, it is uneconomical, which is not preferable.

Examples of the viscoelastic material layer used in the present invention include those formed with the same adhesive as that conventionally used. That is, as a specific example of this adhesive, for example, an acrylate-based adhesive composition obtained by copolymerizing an alkyl acrylate having an alkyl group with 4 to 10 carbon atoms, a lower alkyl acrylate, a lower alkyl methacrylate, vinyl acetate, or the like, Or an unvulcanized rubber composition obtained by blending one or more kinds of natural rubber, styrene-butadiene rubber, butyl rubber, reclaimed reclaimed rubber, etc. with a tackifier, a rubber softening agent, a filler, etc. Is mentioned.

The thickness of this viscoelastic substance layer is 0.05 to 4
mm is preferable, and 0.1 to 3 mm is particularly preferable. If the thickness is less than 0.05 mm, the desired vibration damping characteristics cannot be obtained. On the other hand, if the thickness exceeds 4 mm, the effect of increasing the thickness reaches the limit, which is meaningless, and is uneconomical and increases weight. So undesirable.

The most significant feature of the present invention is that the laminated sheet of the high elasticity constraining layer and the viscoelastic material layer described above,
An adhesive layer is provided on the surface of the viscoelastic substance layer, and the adhesive layer exhibits fluidity at the time of bonding and has an elastic modulus of 1 at room temperature.
It is at a point of 0 ⁶ to 10 ¹⁰ dyne / cm ² .

In the present invention, by adopting such an adhesive layer, not only is it extremely easily adhered to an adherend having a smooth surface, but also the adhesive of this adhesive layer causes the adherend to be rough. As a result of entering the surface and exerting an anchoring effect and improving its adhesiveness, the vibration damping performance is improved in any case.

The adhesive layer may be either a hot-melt type adhesive such as a hot-melt type adhesive or a thermosetting type adhesive such as an epoxy type adhesive.
It shows fluidity when bonded and has an elastic modulus of 10 ⁶ to 1 at room temperature.
It is required to be 0 ¹⁰ dyne / cm ² . As an example of this commercially available product, for example, EVA-flex P-1 manufactured by Mitsui DuPont Polychemical Co., Ltd., which is an EVA hot-melt adhesive, is used.
007.

The thickness of the adhesive layer is 0.01 to
The range of 2 mm is preferable, and the range of 0.05 to 1 mm is particularly preferable. If the thickness is less than 0.01 mm, the desired adhesive strength cannot be obtained. On the other hand, if it exceeds 2 mm, the effect of increasing the thickness reaches the limit, which is meaningless, and increases the weight, which is uneconomical. is there.

[0024]

In the vibration-damping sheet of the present invention, the adhesive layer having the above-mentioned constitution, which adheres to the adherend, exhibits fluidity at the time of adhesion and has an elastic modulus at room temperature of 10 ⁶ to 10 ¹⁰ dyne / cm ^2. Since it is set to, the adhesive not only adheres to the adherend with a smooth surface extremely easily, but also the adhesive of this adhesive layer enters the rough surface of the adherend and exerts the anchoring effect, and the adhesion As a result of improving the property, in any case, it has the effect of improving the vibration damping performance.

[0025]

EXAMPLES The present invention will now be described in detail based on examples, but the present invention is not limited thereto. As shown in FIG. 1, a butyl rubber-based viscoelastic substance layer 3 having a thickness of 2 mm, which is composed of the composition described below, is closely formed on an aluminum foil (high elastic constraining layer) 2 having a thickness of 100 μm, and then,
A vibration damping sheet 1 of the present invention was obtained, which was a laminated body in which an EVA hot melt adhesive layer (thickness: 50 μm) 4 was attached to the exposed surface of the viscoelastic substance layer 3.

In this case, the EVA hot-melt adhesive layer (thickness: 50 μm) 4 has an elastic modulus at room temperature of 10 ⁸ dyne /
What was cm ² was used.

This damping sheet was placed on foamed concrete with a thickness of 10 mm and adhered to each other to obtain a test piece for evaluating damping characteristics.

Composition of viscoelastic material layer Butyl rubber 100 parts by weight Polybutene 80 parts by weight Petroleum resin 40 parts by weight SRF carbon 50 parts by weight Calcium carbonate 100 parts by weight After the above components are sufficiently kneaded with a pressure kneader, a conventional method is used. It was made into a sheet by.

COMPARATIVE EXAMPLE In the example, the one formed in the same manner as in the example was used except that the following hot melt type adhesive layer was used in place of the EVA hot melt type adhesive layer.

Composition of Hot Melt Type Adhesive Layer Styrene-isoprene-styrene copolymer 100 parts by weight Petroleum resin 100 parts by weight Petroleum softener 100 parts by weight

The hot melt adhesive layer (thickness 5
0 μm) has an elastic modulus of 10 ⁵ dyne / cm ² at room temperature.

This damping sheet was placed on foamed concrete having a thickness of 10 mm and adhered to each other to obtain a test piece for evaluating damping characteristics.

Test method (vibration damping characteristics) Using the above-mentioned test pieces for evaluation in which the vibration damping sheets of the examples and comparative examples were attached to foamed concrete, the vibration damping performance of both test pieces was measured by the impulse vibration method. did. The damping effect is determined by the loss coefficient η calculated from the measurement result, and a plot is shown in FIG.

From the results shown in FIG. 2, it is recognized that the example has excellent vibration damping characteristics over the entire measurement frequency range as compared with the comparative example.

[0035]

In the vibration damping sheet of the present invention, the adhesive layer having the above-mentioned constitution and adhering to the adherend is set to have an elastic modulus of 10 ⁶ to 10 ¹⁰ dyne / cm ² at room temperature. As a result, not only can it be adhered to an adherend with a smooth surface quite easily,
The adhesive of this adhesive layer enters the rough surface of the adherend to exert the anchoring effect, and as a result of improving the adhesiveness, the vibration damping performance can be improved in any case, and the desired adhesive strength is also obtained. Is easy to secure, and does not naturally fall after being adhered to an adherend, and does not cause a positional deviation or the like. Therefore, workability is improved even if the surface of the adherend is rough. .

[Brief description of drawings]

FIG. 1 is a sectional view of a vibration damping sheet showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing damping characteristics of an example and a comparative example.

[Explanation of symbols]

 1 Damping Sheet 2 High Elasticity Restraint Layer 3 Viscoelastic Material Layer 4 Adhesive Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Manabu Matsunaga 1-2-1, Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (1)

[Claims] 1. A vibration damping sheet having a three-layer structure comprising a high elastic constraining layer, a viscoelastic substance layer and an adhesive layer, wherein the adhesive layer has an elastic modulus at room temperature of 10 ⁶ to 10 ¹⁰ dyne / Damping sheet characterized by being cm ² .